The structure and reactivity of a low-sulfur lacustrine oil shale (Colorado U.S.A.) compared with those of a high-sulfur marine oil shale (Julia Creek, Queensland, Australia)

•Reactivity of oil shales is not correlated with marine/lacustrine origin.•Big difference in temperature dependence of reactivity•High conversion can be obtained under relatively mild conditions.•Product composition depended on marine/lacustrine origin.•CO2 yields were at most 4.0 wt.% db under all reaction conditions.

Oil shales from two different continents (Australia and North America) of different ages (100 and 40 million years) and origins (one marine, one lacustrine) have been reacted in the range 355–425 °C under H2 or N2 for 1 or 5 h with or without the addition of catalyst. The shales differed in S content, and the nature of the mineral matter, but both had high atomic H/C ratios. The overall reactivity of the two shales was similar and high yields of soluble products could be obtained under relatively mild conditions with only small CO2 yields, but the temperature dependence of reactivity and the effect of potential catalysts differed markedly. Increasing the temperature and time led to increases in conversion but of different extents. Substituting H2 for N2 led to a large increase to conversion for the lower-atomic-H/C ratio marine oil shale. The CH2Cl2 solubles from the marine oil shale showed a larger range of compounds than those from the lacustrine oil shale which resembled the CH2Cl2 solubles from torbanite, a coal-like material derived from lacustrine algae.

Graphical abstractComparison of product yields of Colorado and Julia Creek oil shalesFigure optionsDownload full-size imageDownload as PowerPoint slide